ABSTRACTS: July 1986147-152

(1)

ABSTRACTS

of

current literature on the platinum metals and their alloys

PROPERTIES

An

XPS Study

of

Nitric Oxide, Carbon

Monoxide and Oxygen Adsorption on

Pt(210)

J. F. LANC and R. I. MASEL, surf: sci., 1986,167, (2/3), 261 -270

W S

and AES were used to examine the adsorption of NO, CO and O 2 on Pt(210). Both CO and NO ad- sorb molecularly on R(210), but while CO desorbs without dissociation, NO dissociates on heating to

45oK. 0, adsorbs dissociatively. Two different 0 states are seen by XPS, and the R(210) surface seems to ad- sorb an unusually large amount of

o?.

The Al-Pt (Aluminum-Platinum) System

A. 1. McALISTER and D. J . KAHAN, Bull. Alloy Phase

Diagram, 1986, 7. ( I ) , 47-51> 83-84

The

Al-Pt

phase diagram is discussed. The phase in equilibrium with Al, and the liquid near zoat.%Pt at

657OC are contentious, as is the existence of the high- and low-temperature modification of AlPt ?. Other pro-

blems are examined, and data on crystal structures and lattice parameters are given.

The

Glass Transition Phases

in

the Forma-

tion of Pt-Si

D. M. VANDERWALKER, Phys. Status Solidi A , 1986,94, ( I ) , 77-81

A crystalline to amorphous transition occurs at the Pt-Si interface during the formation of PtSi. The structure of the glassy phase depends on temperature. At higher temperatures the glassy phase contains small random- ly oriented Pt crystals; while the lower temperature glass has a continuous amorphous structure. When

R

diffuses into Si a crystalline-amorphous transition oc-

curs, when the elastic energy of the crystalline solid is increased and the energy barrier for the reaction is lowered. PtSi nucleates within the glass at one interface.

Metallic Conduction through Langmuir-

Blodgett Films

Solid Films, 1986, 135, (2), 173-182

The mechanism giving rise to high electrical conductivity was examined in Au-Pd/Cd stearatelAu and &/a-

tricosenoic acid/Ag systems, where the Cd stearate and w-tricosenoic acid are Langmuir-Blodgett fdms. Metallic pathways, of area 6 x IO-' pm,, exist through the LB films, even for relatively thick multilayers ( N= 4 o layers). Switching effects were observed in these filaments on the application of voltage pulses.

N . R. COUCH, C. M. MONTGOMERY and R. JONES, Thin

Phase Relationships in the Ternary System

U-Nd-Pd

D. C. PARNELL, N . H. BRETT, H. R . HAINES and P . E. PO'ITER,J. L.ess-CommonMet., 1986,118, ( I ) , 141-152

Phase equilibria in the U-Nd-Pd system have been obtained by a variety of techniques. Also information on

the binary phase diagrams for U-Nd, U-Pd and Nd- Pd is reviewed. Data obtained from quenched and an- nealed samples show that a liquid immiscibility gap ex- ists within the system. Solid state tie lines have been determined.

Hydrogen Chemisorption on, and

Diffusion through, Palladium Clusters

N. A. BAYKARA, J. ANDZELM, D. R . SALAHUB and

s. z.

BAYKARA, h i .

3.

Quantum Chem., 1986, 29, (4),

Computations were performed for PdH, Pd,H and for a series of Pd ,"H clusters representing H chemisorb- ed on a (111) surface and at various sites along a diffusion path through the cluster. The calculated chemisorption geometry has a Pd-H distance of I . 7 2 i . 1025-1032

CHEMICAL COMPOUNDS

Redox Properties of the 0x0-Bridged

Osmium Dimer[

(bpy),(OH,)OslllOOs'V(O-

H)(bpy),I4+. Implications for the Oxida-

tion of H,O to 0,

Chem. Soc., 1986, 108, (7), 1493-1501

The 0x0-bridged

0s

dimer title compound has been isolated and characterised. Electrochemical experiments have revealed an extensive redox chemistry for the dimer based couples, for example

os(v)os(v)/os(Iv)0s(v).

J . A. GILBERT, D. GESELOWITZ and T . 1. MEYER,J. Am.

The Next Generation

of

(Po1yazine)-

Ruthenium(I1) Complexes

K. J. BREWER,

w.

R . MURPHY, s. R . SPURLIN and J . D.

The synthesis and characterisation of a new and highly luminescent Ru complex, Ru(dpp): +

(dpp) = 2,3-bis(2-pyridyl)pyrazine, is reported. The Ru(dpp): + excited state lifetime is shorter than that

of the bpy analogue, but the former complex has a greater advantage in energy storage and transfer reactions. Dpp can bind as a chelate to a second metal centre, enabling the Ru(dpp): + complex to be the centre for formation of complexes capable of intramolecular energy- or electron-transfer reactions.

PETERSEN, InOrg. Chem., 1986, 25, (6), 882-884

(2)

Synthesis and Sintering of Mixed Metallic

Oxide Conductors Nd2-,Cu,Ru20,-,

(Paris), Colloq. I , 1986, (21-85543-859

Pyrochlore type phases Nd, -xCuxRu,O, - x were

synthesised up to x=0.375. Samples with good compactness have good metallic conductivity, but those with bad compactness behave as semiconductors. Good sintering has been obtained with the addition of 5wt.%CuO. Samples sintered with CuO are then metallic, for all values of x except 0.

A. HAOUZI, J . MULLER and J . C. JOUBERT,

3. P h p .

ELECTROCHEMISTRY

Electrochemical Behavior and Surface

Structure

of Pt

Thin

Film Electrodes

Deposited

on

Molecularly Smooth Mica

M. MAEDA, H. S. WHITE and D. J. McCLURE,

3. Elec-

iroanal. Chem. Interfacial Electrochem., 1986, zoo, (I and 2), 383-387

A preliminary note on results of the preparation and characterisation of IOMI thick semitransparent Pt

fdm electrodes with an average surface roughness of ~ n m is presented. The electrochemical behaviour of the electrodes was qualitatively similar to that of macroscopic polycrystalline Pt electrodes. The Pt/mica structures are well suited for electrochemical studies and in thin-fdm technology.

Effect of Electrochemical Pretreatment

on

Catalytic

Activity

of

Bismuth

Ruthenate Electrodes for Oxygen Evolu-

tion

in

Alkaline Solution

c . IWAKURA, T. EDAMOTO and H. TAMURA, Bull. Chem. SOC. Jpn., 1986, 59,

(21,

145-148

The catalytic activity of a fdm-type Pt/Bi,Ru,O, electrode for 0,evolution was greatly enhanced by an

electrochemical pretreatment, including potential holding and cycling. However no appreciable enhancement in catalytic activity was observed for a pellet-type Bi,Ru,O,. The pretreatment effect was explained by the participation of higher valence Ru species in the 0 evolution reaction.

Polarization Behavior and Components

of Internal Resistances of Semi-Polar

Type Pt-SPE (Nafion 315) Electrodes

K . FUJIKAWA, H . ISHIKAWA, H. NAKAJIMA and H. KITA, Denki Kagaku, 1986, 54, (I), 55-59

The electrochemical behaviour of a Pt-SPE (Nafion 325) electrode was investigated for H ionisation and

0 reduction reactions by polarisation. The 0 reduction and the H ionisation are examined as polarisation curves by reference to Tafel slopes, Ohm’s law and the limiting current, depending upon the potential, gas pressure and type of reaction. It is concluded that a semimicro model of the Pt-SPE electrode is ap- plicable when the catalytically active zone is just in- side the membrane surface, embedding

Pt.

An

X-Ray

Photoelectron Spectroscopic

Study of Electrocatalytic

Activity

for

Chlorine

Evolution

on

Amorphous

Palladium-Phosphorus

Alloys

Containing

Rhodium, Iridium

or

Platinum

Electrochim. Acta, 1986, 31, (4), 481-488

The electrocatalytic activity for C1, evolution was examined in terms of the surface fdm formed on amorphous Pd-base alloy anodes during hot concentrated NaCl electrolysis. C1, occurred on the surface fdm where cations were Rh, Ir or Pt. Amorphous Pd-Ir-P alloys had high activity for C1, evolution, while Pd- Rh-P and Pd-Pt-P alloys needed high overpotential for C1, evolution. A large amount of

Cl,

was found

on the surface of amorphous Pd-Rh-P and Pd-Pt-P alloys polarised at high overpotentials.

Indirect Electrooxidation of Alcohols and

Aldehydes by Using

a

Double

Mediatcnry

System Consisting of RuO4/RuO2 and

C1’ ICI- Redoxes in an Aqueous-Organic

Two-Phase System

S. TORII, T. INOKUCHI and T. SUCIURA,

J.

@g. Chem.,

1986, 51, (2), 155-161

The utility of a double mediatory system consisting of RuO,/RuO, and Cl+/CI- redox couples for the in-

direct electrooxidation of alcohols and aldehydes has been examined. RuO, oxidised the substrate, then RuO, was regenerated from RuO, by C1, or IC11+, and the C1 ion was oxidised to

IC11+

on the anode in the aqueous layer. The simplicity of product isolation and low cost of the oxidants make this an alternative to standard methods of oxidation. Secondary alcohols were oxidised to ketones, and primary alcohols and aldehydes were oxidised to carboxylic acids.

M. HARA, K. ASAMI, K. HASHIMOTO and T. MASUMOTO,

PHOTOCONVERSION

Photochemical Hydrogen Production

with Platinized Suspensions of Cadmium

Sulfide and Cadmium

Zinc

Sulfide

Modified by Silver Sulfide

J.-F. REBER and M. RUSEK,

3.

Phys. Chem., 1986, 90,

(51, 824-834

Active photocatalysts for the photochemical production of H, can be prepared by Pt deposition on

microcrystals of pure

C d S

powders with very small (<6.7mZ/g) specific surface areas. The H, evolution comes from irradiating suspensions of platinised

C d S

in solutions of

Sz-

and/or SO:- ions. Also Ag,S coprecipitated with C d S or surface modification of

C d S with large (>>Ioom*/g) specific area by Ag+

(3)

Polymer Viologen as

a

Stabilizing

Agent

of

Colloidal Platinum for Photoinduced Elec-

tron

Transfer Reactions

Y . NOSAKA, A. KUWABARA and H. MIYAMA,

3.

Photochem., 1986, 32, (2), 143-150

Photoinduced electron transfer and H evolution were investigated using colloidal Pt stabilised by viologen- pendant Nylon (Pt-PV"). From laser flash photolysis experiments the Pt-PV'+ was found to accept direct-

ly an electron from excited ZnTMhP'+, and the reverse electron transfer was retarded by the positive charge of the protecting polymer, while no net electron transfer was observed for colloidal

Pt

stabilised by PVA. The quantum yield of H production with a Pt-PVz+ catalyst was a factor of 7 higher than with

Pt-

PVA, and reached 0.38.

Colloidal Platinum Protected by

Polymerized Micelle. Preparation and Ap-

plication

to

Catalysis for Photochemical

Hydrogen Generation from

Water

N . TOSHIMA, T. TAKAHASHI and H. HIRAI, Chem. Lett. JPn., 1986,

(0,

35-38

Colloidal Pt protected by polymerised micelles was prepared by the photoreduction of chloroplatinic acid in the presence of unsaturated surfactants, and the subsequent u.v.-polymerisation of the surfactants.

This

colloidal Pt acts as an active catalyst in the ED- TA/Ru(bpy)

:

+/MVz + system.

Photoresponsive Graphite Electrode

Coated with Bilayer Membranes of

Prussian Blue and Polymer-Pendant

M. KANEKO and A. YAMADA, Electrochim. A m , 1986,

Graphite electrodes were made photoresponsive by coating with bilayer membranes of Prussian blue and polymer-pendant Ru(bpy) +

.

A photocurrent was induced by irradiating the coated electrode, which was dipped in aqueous electrolyte. Photocurrent depends on the applied potential, and the major process for photocurrent generation concerns the excitation of the Ru complex.

Photodynamics of the Tris (2,2I-bipy-

razine)Ruthenium(2

+

)/Methylviologenl

EDTA System in Aqueous Solution

D. R. PRASAD and M.

z.

HOFFMAN,

3.

Am. Chem. Soc., 1986, 108, (IO), 2568-2573

Luminescence quenching and flash photolysis have been used to study the photodynamics of the title system in aqueous solution. The quantum yields were found in acid, neutral and alkaline solutions. Ru(bpz): + is concluded to be a superior photo- sensitiser than Ru(bpy):+ because its excited state favours reductive quenching by sacrificial electron donors, the oxidised forms of which can undergo rapid irreversible transformation.

RdbPY)?

31,

(21,

273-275

Photodecomposition of H,S in Aqueous

Alkaline

Media

Catalyzed

by

Ru0,-Loaded

Alumina in the

Presence of

Cadmium

Sulfide. Application of the Inter-

Particle Electron Transfer

Mechanism

E. BORGARELLO, N. SERPONE, M. GRiiTZEL and E. PELIZZETTI, h r g . Chim. Acta, 1986,112, (2), 197-2001 The photodecomposition of H,S by visible light >400nm has been investigated in o.Im Na,S and IMNaOH in the presence of CdS dispersions and in CdS+ AI,O,/RuO, mixtures. A 5-fold increase in the

H, evolution rate is obtained through the coupling of the excited semiconductor and the redox catalyst. Data are interpreted by the inter-particle electron transfer pathway. The engineering energy efficiency is estimated at 1.2% from the total incident light energy and the heat of combustion of H,

.

Photogeneration of Hydrogen and Sulfur

on

PolypyrrolelRuO, Modified Silicon

Powder

8. c. CHUN

w, s.

KAPUSTA and N. HACKERMAN,

3.

Elec- trochem. Soc., 1 9 8 6 , 133, (9, 934-935

The illumination of polypyrrole/RuO, loaded Si particles dispersed in aqueous sulphide solutions results in the generation of large amounts of H, and colloidal S (or polysulphides). The

S

is removed with a current efficiency >go% and quantum efficiency of

-

1%.

Surface Structure and Properties of

Zeolite-Supported Transition Metal Oxide

Catalysts for Photooxidation of

Water

to

Oxygen

Catal. (Dalian, China), 1986, 7, ( I ) , 60-66 Surface structure and properties of R u 0 , N and Fe0,N zeolite catalysts were studied by various techniques. RuO, N

+

FeO,N( I) contains many more acid sites than the corresponding co-impregnated catalyst (Ru0,-FeOx)/Y(2). (I) and (2) have quite

dif-

ferent properties, composition and morphological structure.

M.-X. YANG, C.-L. LI, Y.-M. ZHANG and C.-L. GU,

3. ELECTRODEPOSITION AND

SURFACE COATINGS

Electroless Plating for Electronics

w. J.

HAWK, Metal Finish., 1986, 84, (3), 11-12

Properties of electroless Pd, operating characteristics, solderability and contact resistance are discussed. Elec-

troless plating without a Au overlayer is cost effective and provides equivalent or improved performance over previously used Au fmishes. Wear cycle life increases from 100,000 for 50 microinches of Au to >IO* for 50 microinches of Pd. A dual

tank

system is recommended and 50 microinches is proposed to provide the desired properties.

(4)

Gold Flashed Palladium Nickel for Elec-

tronic Contacts

K . J. WHITLAW, Trans. Inst. Met. Finish., 1986, 64,

( 2 ) , 62-67

The results of comparisons between Pd-Ni and acid hard Au in high speed plating applications shows that similar plating rates can be achieved by using a new high speed Pd-Ni process. Tables of mechanical endurance and industrial atmosphere tests, and current switching valves are given for Pd-Ni/Cu, Pd-Ni/Ni, Au flash/Pd-Ni/Cu and Au flashmd-Ni/Ni. The Pd- Ni electrolyte produces a deposition rate of 18pm/min during high speed plating. It was found that Au flashed Pd-Ni is a suitable alternative to acid hard Au.

LABORATORY APPARATUS

AND TECHNIQUE

Platinum Black Powder a8 a Heat

Ex-

changer Material at Low Temperatures

P . R. ROACH, Y. TAKANO, R. 0. HILLEKE, M. L. VRTIS, D. JIN and B. K . SARMA, Cryogenics, 1986, 26,

(9,

319-321

A procedure for producing a thin layer of sintered

Pt

powder with a very large surface area, relatively low electrical resistivity and a reasonably small void volume has been developed for use in cooling He to low temperatures.

A

Proton-Injecting Technique for the

Measurement of Hydration-Dependent

Protonic Conductivity

1986, 19, (I), 80-82

A technique for injecting protons directly from a H-

saturated Pd black electrode into a solid sample is described. This technique could be used for measurements on H bonded solids, crystalline ionic hydroxides and acids, ceramics and biopolymers. Pd black electrodes can reversibly absorb H to p o

volumes of

H,

at NPT. In the Pd lattice the dissolved

H is almost completely ionised. The conductivity cell where the sample under test is between two Pd black electrodes is described.

H. MORGAN, R. PETHIG and G. T. STEVENS,

3.

Phys. E ,

HETEROGENEOUS CATALYSIS

Kinetics and Reaction Pathways of

Methanol Oxidation on Platinum

R. W. McCABE and D. F. McCREADY,

3. Phys. Chem.,

1986, 903 (7), 1428-1435

Methanol oxidation rates on Pt wires in a flow reactor at pressures go-13oPa were studied as functions of oxygen-to-methanol equivalence ratio and wire temperature. Methanol oxidation followed two paths, a major pathway involving H,CO and CO in- termediates and a minor pathway involving an elemental C intermediate.

Cyclic Operation of Pt/Al,O, Catalysts

for CO Oxidation

B. K. CHO and L. A. WEST, lnd. Eng. Chem., Fundam.,

An examination of CO oxidation over well- characterised Pt/AI? 0, catalysts in an integral reactor under forced feed composition cycling is presented to determine improvements in the cyclic performance of automotive catalysts. The most effective CO oxidation strategy is a hybrid scheme based on cyclic operation during the warm-up period to 300°C, then steady state operation at temperatures >300°C.

Selective Conversion of Propane into

Aromatics on Platinum Ion-Exchanged

Gallium-Silicate Bifunctional Catalysts

Chem. SOC., Chem. Commun., 1986, (7), 571-573 Novel

Pt

ion-exchanged Ga silicate bifunctional catalysts have been developed. The catalysts produced aromatics from propane more actively and selec- tively than previously developed catalysts.

Oxygen Storage in Automobile Exhaust

Catalyst

I. S. METCALFE and S. SUNDARESAN, Chem. Eng. sci.,

Charge transfer reactions between a p t catalyst and

Y-

stabilised zirconia support were studied electro- chemically during CO oxidation over a range of com- positions and temperatures typical of automotive exhausts. A model for the participation of the support in the oxidation reactions is derived. It is estimated that the contribution of the charge transfer reactions occurring at the three-phase interface between Pt,

YSZ and the gas phase, to the total area of CO oxidation is negligible under steady conditions.

Platinum-Rhodium Synergism in Three-

Way Automotive Catalysts

S. H. OH and 1. E. CARPENTER,

3.

Catal., 1986,98, ( I ) ,

178-190

The interactions between

Pt

and Rh in three-way automotive catalysts were investigated with a

Pt-Rh

bimetallic catalyst and a mixture of Pt and Rh mono- metallic catalysts, while keeping the amount of each noble metal constant. CO oxidation for the bimetallic catalyst was substantially higher than for the mixture, over converter warm-up conditions.

Method for the Selective Hydrogenation

of Polyunsaturated Hydrocarbons in

Olefmic Hydrocarbon Mixtures

F. NIERLICH and F. OBENAUS, Erdoel Kohle Erdgas Petrochem., 1986, 39, (z), 73-78

The qualitative and selective hydrogenation of polyunsaturated hydrocarbons, such as dienes or acety- lenes, in olefinic hydrocarbon mixtures, to the corresponding monoolefins occurs over a Pd/AI,O, or Pd/C catalyst in the presence of a few ppm of CO. 1986, 2 5 , (I), 158-164

T. INUI, Y. MAKINO, F. OKAZUMI and A. MIYAMOTO,

3.

(5)

NO Reduction Activity of Pd

Catalyst

Modified with Rare Earth Oxides

Nippon Kagaku Kaishi, 1986,

(z),

130-137 The reduction of NO on fresh and aged Pd-rare earthla-Al

,

0,

catalyst was investigated using simulated exhaust gas as NO. NO conversion at lower temperatures was better with Pd-rare earth catalysts than with unmodified Pd. La, Nd and Sm were the most effective additions to Pd. Except for Pd-Ce the Pd-rare earth catalysts had better activities and selec- tivities below 300OC for the NO-H, reaction than Pd.

Studies of the Interactions of H, and CO

with Pd/SiO, Promoted with La203,

CeO,, PrbOll, Nd203 and Sm,O,

H. MURAKI, M. FUKUI, K. YOKOTA and Y. FUJITANI,

I. S . RIECK and A. T. BELL,

3.

cazal., 1986, 99, (2), 278-292

The interactions of H , and CO with promoted Pd/SiO, were investigated by various techniques. The promoter partially covers the Pd particles, and on reduction parts of the promoter in contact with Pd are reduced. The partially reduced rare earth oxide species covering the Pd reduces the amounts of H, and CO that can be adsorbed on the metal. The rare

earth oxide moieties have a slight influence on H ,

adsorbed distribution but cause a significant change in the distribution of CO adstates.

Soybean

Oil

Hydrocracking under

Pressure: Process and General Aspect of

the Transformation

MARIADASSOV, Rev. Inst. Fr. Pet., 1986, 41, (3), 421-432

A process for studying the hydrocracking of vegetable

oils into gasoline and diesel fuel fractions while limiting polymerkation and coking is proposed. The hydrocracking utilised an oxide or a dual-function t%rhodium/silica catalyst. During the hydrogenatingkrackg with 2%Rh/SiO, the double bonds of the lateral chains of triglycerides were hydrogenated on heating to -673K, when hydrocracking began. At 673K the decarbonylation/decar- boxylation of fatty acids is observed.

Trifunctional Catalysts for Conversion of

Syngas to

Alcohols. Fifth Quarterly

Report, September

1 -November 30,

1985

Chemistry, I S April 1986, 86, (IS), 8-9

The individual reaction products formed during CO hydrogenation over

Rh

catalysts have been identified and contain significant amounts of alcohols, aldehydes, acids, esters, ethers, CI to C5 hydrocarbons, CO, and H,O. Na-Rh/Al,O, catalyst was used in CO hydrogenation; the selectivity to oxygenates decreased with increasing conversion, and C, oxygenates were

-

80% of all oxygenates formed. P. P. NUNES, D. BRODZKI, G. BUGLI and G. D. JEGA-

K. B. BISCHOFF, W. MANOCUE and G. A. MILLS, NTIS

Hydrogenation

of

CO and

CO,

on

Car-

bon Black-Supported Ru Catalysts

I. RODRfGUEZ-RAMOS, F. RODRfGUEZ-REINOSO, A. GUERRERO-RUIZ and J . DE DIOS L6PEZ-GONZALE2,

3.

Chem. Technol. Bwtechnol., 1986, 36, (z), 67-73 The activity and selectivity of unsupported Ru and Ru/C black catalysts for the hydrogenation of CO and CO? has been examined in terms of particle size effects. The specific activities for both reactions decreased with metal particle size, and the product distribution for CO hydrogenation was also a function of metal dispersion. CO, hydrogenation yields only CH,. Thus the proportion of CH, produced increases and the o1efm:paraffin ratio decreases with decreasing Ru particle size.

HOMOGENEOUS CATALYSIS

Reactions of Rh(acac)[P(OPh),], with H,,

CO and Olefms

A. M. TRZECIAK, 1. I . ZIOLKOWSKI,

s. AYGEN

and R.

The reactions of the title compounds have been studied by various techniques. In the presence of H, and free phosphite, Rh(acac)P, produces HRhP,

,

which catalyses the isomerisation of olefms. Adding CO to HRhP, produced HRh(CO)P,, which was a good hydroformylation catalyst. The latter hydride can be directly obtained from the starting complex in the presence of H,, CO and free phosphite.

Catalytic Reactions of Metalloporphyrins.

1. Catalytic Modification of Borane

Reduction of Ketone with Rhodium(II1)

Porphyrin

as

Catalyst

OGOSHI,

3.

Am. Chem. Soc., 1986, 108, ( 5 ) . 943-947 A highly efficient catalytic modification of synthetic reactions of borane in the presence of 0, is provided by a Rh porphyrin catalyst. The Rh-BH, complex can transfer borane to ketone, do a facile oxidation with 0, and easy hydrolysis with H,O.

Chemistry and Catalytic Properties of

Ruthenium and

Osmium

Complexes. 3.

Development of Highly Active Systems

for

the Homogeneous Hydrogenation of

Aldehydes and Ketones

R. A. SANCHEZ-DELGADO, N. VALENCIA, R.-L.

Chem., 1986, 2 5 , (8), 1106-1r11

The development of highly efficient catalytic systems from 19 Ru and

4 0 s

complexes containing hydride, phosphine and carboxylate ligands under moderate reaction conditions is described for the catalytic hydrogenation of aldehydes and ketones to yield the

corresponding alcohols. For complexes MHX(CO)(PR,)

,

the catalytic activity is dependent on X (halide), but independent of R.

VAN ELDIK,

3. Md.

catal., 1986, 34, (3)- 337-343

Y. AOYAMA, T. FUJISAWA, T. WATANABE, H. TO1 and H.

MhQUEZ-SILVA, A. ANDRIOLLO and M. MEDINA, InOrg.

(6)

Homogeneous Multimetallic

Catalysts.

Part

6. Hydroformylation

and Hydro-

esterification of Olefms by Homogeneous

Cobalt-Ruthenium Bimetallic Catalysts

Mol. Catal., 1 9 8 6 , 35, (I), 29-37

The Co,(CO),-Ru,(CO),, system showed high catalytic activity for hydroformylation of olefins such as cyclohexene, I-hexene and styrene compared to the catalysts singly. The hydroformylation reaction was much influenced by the solvent used, and methanol and ethanol were the best of those employed.

M. HIDAI, H. FUKUOKA, Y. KOYASU and Y. UCHIDA,

7. Oxidation of Alcohols with Ally1 Methyl

Carbonate by

Means

of Ruthenium Catalyst

I. MINAMI, M. YAMADA and 1. TSUJI, Tetrahedron Lett., 1986, 27, (16), 1805-1808

Oxidation reactions for alcohols were attempted with various Pd,

Rh

and Ru catalysts. It was found that for secondary and allylic alcohols Imol.% of Ru catalysed reactions with ally1 methyl carbonate giving ketones or a,p-unsaturated aldehydes.

FUEL CELLS

Electrocatalysis by Electrodeposited Pt

from PtCla- Confined in

a

Langmuir-

Blodgett Film on

a

Glassy Carbon

Electrode

M. FUJIHARA and

s.

FQOSITTISAK,

3.

Electroanal. Chem. Interfacial Electrochem., 1986, 199, (2), 481-484

A novel

Pt

modified

GC

electrode with a much lower loading level and similar activity to smooth Pt has been developed using the Langmuir-Blodgett technique. The overlay is so thin ( -

~onm)

that the high catalytic activity cannot be limited by mass transfer through the fdm. The electrodes are designed for fuel cells. Cyclic voltammograms are presented.

CHEMICAL TECHNOLOGY

Application of Platinum Gauze Activated

by Hydrogen to

the

Adsorption Separation

of Silver Traces and Their Determination

by AAS

or

Spectrophotometry

Tulanta, 1986, 33, (2), 155-160

The separation of Ag from Cu by deposition through internal elecuolysis with H adsorbed on a

Pt

gauze electrode surface is described. The H adsorbed on the

Pt

gauze lowers the electrode potential, allowing Ag traces to be deposited. The Pt surface activation by H can be achieved either electrolytically or by passing

H,

through the solution in which the Pt is immersed. Ag

can then be stripped from the gauze electrode. This method can also be used for purification of reagents containing Ag traces.

Z. BOGUSZEWSKA, M. KRASEJKO and B. PALMOWSKA-KUS,

ELECTRICAL AND ELECTRONIC

ENGINEERING

High Output Power Hydrogen Engine with

High Pressure Fuel Injection,

Hot

Surface

Ignition and Turbocharging

s. FURUHAMA and T. NKUMA, Inr.

J .

Hydrogen Energv, 1986, 11, (61, 399-407

A high power two-stroke diesel turbo engine has been developed, with the hot surface of the porcelain ignition plug having a

Pt

wire wound around it. Current is only switched to the wire at low temperature and low load. Pressurised liquid H, is directly injected in-

to the combustion chamber through eight flows, but only one flow at a time reaches the hot surface.

Novel Process for Direct Conversion of

Free Energy of Mixing

into

Electric Power

Process Des. D e n , 1986, 25, (2), 443-449

The direct conversion of salt gradients into electric power with the production of an acid and a base at the same time was examined. Devices combining features of an electrodialytic pile and those of fuel cells or of electrochemical half cells were designed. Electrodes were made by depositing

Pt

on active charcoal catalyst

on a C cloth. Fuel cells used H , 0 as the fuel, and air as the oxidant. Energy extracted from salinity gradients at power densities of up to I Wlm’ of the membrane yields up to o.6MW of electric power per m’/s of river or brackish water.

J. JAGUR-GRODZINSKI and R. KRAMER, Ind. End. C h m . ,

Graphoepitaxy of Platinum

on

Sawtooth

Profile Gratings

K. KUSHIDA, H. TAKEUCHI, T. KOBAYASHI and K. TAKAGI, Appl. Phys. Lett., 1986, 48, (12), 764-766

The graphcepitaxies of

Pt

fdms on sawtooth profiles gratings have been examined by SEM.

Pt

was evaporated to different thicknesses onto (1oo)Si wafer gratings of o.#m period. Pt fdms Imnm thick have crystallites of grain size of about one grating period wide and 0.5-5pm long embedded in the gratings. Con- tinuous fdms with (100) orientation are produced after further deposition and annealing.

Reliability of Germanium Avalanche

Photodiodes for Optical Transmission

Systems

n.

SUDO, Y. NAKANO and G. IWANE, IEEE Trans. Elec- tron Devices, 1986,

ED-33,

( I ) , 98-103

Over 600 Ge avalanche photodiodes (APD) for use in undersea optical transmission systems have been examined. The failure rates during high-temperature storage, high-temperature operation and surge endurance are discussed. The main failure of Ge-APDs

was abnormal breakdown due to

Al

penetration from metallisations into Ge at temperatures above 20o0C. When Au/Pt/Ti metallisations were used the Ge-AFTk